Methods of and apparatus for aligning and bonding workpieces

ABSTRACT

Bonding machines have transparent elements on their bonding axes. Magnified optical means are positioned to view bonding tips and integrated-circuit chips simultaneously through the transparent elements thereby facilitating alignment of the chips to the tips. In one embodiment a bonding tip is transparent and a transparent compliant bonding member is utilized in conjunction with the tip to produce compliant bonds. Another embodiment utilizes a transparent tip in a &#34;hard tip&#34; type of bonding operation. A third embodiment utilizes a transparent tray closely positionable to the bonding tip. After alignment of the tip to one of the chips is achieved the tray is removed and bonding proceeds on an accurately positioned substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods of and apparatus for bondingworkpieces together wherein rapid and accurate alignment of workpiecesto a bonding tip is achieved. In particular, the invention relates tosystems wherein viewing of the workpieces and the tip to which alignmentis to be achieved is performed through transparent elements on thebonding axes of machines used for making the bonds.

2. Description of the Prior Art

In apparatus used for bonding electronic devices such asintegrated-circuit chips to substrates, one of the principal problems isaligning the integrated-circuit chips to bonding tips or apertures incompliant bonding members, then engaging the chips to the tips orapertures, and aligning the chips with a pattern on a substrate. A broadspectrum of optical systems have been utilized to facilitate suchalignment. Most of the systems have some inherent limitations and arethus not entirely satisfactory.

One of the most common systems employs a half silvered mirror suspendedbetween a bonding tip and a plane on which either chips or a substratelie. An optical axis of a microscope is obliquely directed to the halfsilvered mirror and an image of both the tip and a chip or substrate onthe plane over the mirror appear simultaneously in the microscopeeyepiece. However, the oblique viewing causes perspective distortionsand accurate alignment is difficult to achieve because of suchdistortions. Additionally, because the mirror is suspended between thetip and the workpiece with which the tip must be engaged, the mirrormust be mounted on a swing-away mechanism which adds complexity to thebonding apparatus.

The oblique viewing problems associated with half silvered mirrors areeliminated to a certain extent through the use of beam-splitter prismcombinations which are suspended similarly to the mirror but whichdirect an image of both a tip and a workpiece perpendicularly of abonding axis on which it is suspended. These combinations however,require very accurate alignment to the bonding axis and thus thesupporting mechanism, in addition to being capable of swinging away fromthe bonding axis, must have adjustments provided thereon to achieveprecise planar alignment of the prism.

Systems employing reference reticles have also been used to accomplishthe desired alingments. Such systems are described in U.S. Pat. No.3,477,630 issued to F. J. Schneider on Nov. 11, 1969. These systems,while performing admirably when properly adjusted, do suffer from thelimitation that accurate alignment of a mechanism which positions amovable head requires very precise adjustment with respect to thereference reticle in order to achieve the necessary degree of accuracy.

Even more complex systems have been utilized employing rapidlyoscillated mirrors to project images of workpieces and bonding tipssimultaneously to an operator while an operator tries to achievealignment therebetween. Obviously, systems that use oscillating mirrorssuffer from problems associated with inherent complexity.

Except for the reference reticle system, the above described systemshave one common shortcoming. Some optical element of the apparatus mustbe at least temporarily suspended between the bonding tip and theworkpiece. In order to provide space for these elements, the bonding tipmust travel extensive distances in accomplishing either engagement withthe workpiece for pickup purposes or for bonding purposes. Extensivetravel of the bonding tip inherently carries with it difficulty inproviding precise positioning of the bonding tip throughout its range ofoperation.

SUMMARY OF THE INVENTION

It is an object of the invention to provide systems for facilitatingrapid and accurate alignment of workpieces and force-producing elementsin bonding apparatus.

It is another object of the invention to provide systems whereinforce-producing elements in bonding apparatus are required to move onlyvery short distances.

It is a further object of the invention to provide bonding apparatus inwhich workpieces and force-producing elements can be viewed in a directline of sight along a bonding axis.

It is a more particular object of the invention to provide systemswherein bonding of workpieces can be performed under continuous visualsurveillance.

It is an even further object of the invention to provide bondingapparatus wherein the workpieces can be observed during bondingtherebetween so that distortions of the beam leads caused by bonding canbe controlled in response to the viewing thereof.

The foregoing and other objects are accomplished in accordance with theinvention by utilizing transparent elements positioned on bonding axesof bonding apparatus. Workpieces are aligned to force-producing membersin response to images of the workpieces and the members which passthrough the transparent elements.

Particular examples of apparatus useful in practicing the inventioninclude bonding apparatus with transparent bonding heads, bondingapparatus which employs transparent film as a compliant bonding mediumand bonding apparatus in which workpieces are supported on a transparentworkpiece-supporting tray which swings away from a bonding axis after aworkpiece is aligned and engaged with a bonding tip in response to animage passing through the tray.

DETAILED DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will be more readilyunderstood from the following detailed description of specificembodiments thereof when read in conjunction with the appended drawingsin which:

FIG. 1 is a perspective view of one embodiment of the inventiveapparatus;

FIG. 2 is a partially sectioned elevation view of a bonding head portionof the machine of FIG. 1;

FIG. 3 is a view of a monitor portion of the machine of FIG. 1 showing aworkpiece misaligned with respect to a portion of the machine;

FIG. 4 is a view of the monitor of FIG. 3 showing the workpiece aligned;

FIG. 5 is a view of the monitor of FIG. 3 showing a misalignment of asecond workpiece;

FIG. 6 is a view of the monitor of FIG. 3 showing an alignment betweenthe two workpieces;

FIG. 7 is a partially sectioned elevational view of a bonding head whichis an alternate embodiment of the invention apparatus;

FIG. 8 is a view of the monitor of the machine of FIG. 1 showingportions of the bonding head of FIG. 7;

FIG. 9 is a view of the monitor of FIG. 8 showing alignment between aworkpiece and portions of the head of FIG. 7.

FIG. 10 is a view of the monitor of FIG. 9 showing an additionalworkpiece;

FIG. 11 is a view of the monitor of FIG. 10 showing the workpiecesbonded together;

FIG. 12 is an elevational view of a bonding machine which is analternate embodiment of the inventive apparatus;

FIG. 13 is a view taken along the lines 13--13 of FIG. 12 showing amonitor which is portraying a workpiece and a bonding tip;

FIG. 14 is an elevational view of the machine of FIG. 12 in a workpiecepickup position;

FIG. 15 is a view taken along the lines 15--15 of FIG. 14 showing atransparent tray supporting a number of workpieces;

FIG. 16 is a view of the monitor of FIG. 13 illustrating a workpiecealigned with a bonding tip;

FIG. 17 is a view of the machine of FIG. 12 showing the machine in abonding configuration and on which a portion of a support tray has beenremoved for purposes of clarity;

FIG. 18 is a view taken along the line 18--18 showing a substratepositioned for bonding on a bonding axis of the machine of FIG. 17.

DETAILED DESCRIPTION

Illustratively, the invention is described in connection with bondingbeam-lead integrated-circuit chips to conductive elements which arepattern generated on ceramic substrates. However, it is to be understoodthat the invention can be useful in the bonding of many types of smallarticles where accurate alignment between parts is important.

One embodiment of the inventive apparatus a compliant bondig machine,designated generally by the numeral 20, is illustrated in FIG. 1. Thebonding machine includes a movable head assembly, designated generallyby the numeral 22, a base 24, a conventional positioner assemblydesignated generally by the numeral 26, and an electronic optical systemincluding a television camera, designated generally by the numeral 27and a monitor designated generally by the numeral 28. Even though themachine 20 is illustrated with an electronic optical system however, aconventional microscope might also be used with equal effectiveness.

Operation of the machine 20 can best be understood by a discussion anddescription of one complete bonding cycle. As illustrated in FIG. 1, abeam-lead integrated-circuit, designated generally by the numeral 30, isillustrated on a screen 32 of the monitor 28. The image on the screenillustrates leads 36 of the chip 30 being well aligned with conductiveelements 38 which are patterns generated on a ceramic substrate,designated generally by the numeral 40.

At the point in time shown in FIG. 1, the monitor 28 is showing an imageof the chip 30 engaged with a bonding aperture 42 of a compliant member,designated generally by the numeral 44. The compliant member 44 istransparent and for this reason, the substrate 40 below the compliantmember is visible through the optical system 28.

One example of a material suitable for use as the compliant member 44 ispolyimide film. One example of such a film is marketed by E. D. DuPontDeNemours and Co. of Wilmington, Delaware under the tradename "Kapton."By way of example, a film thickness of 0.005 inch has been found to besuitable for chips which are approximately 0.002 inch thick.

For increased visability, the compliant member 44 may be colored.Sensing the color is done readily with a microscope but an electronicoptical system must have color sensing capability to take advantage ofthe additional visibility which color imparts to the compliant member44.

The chip 30 is held in engagement with the compliant member 44 by vacuumdeveloped within a bonding head, designated generally by the numeral 46.The inner structure of the head 46 is more clearly illustrated in FIG.2. A vacuum chamber 48 is formed in the ram 46 and is connected to avacuum source 49 through a port 50 and tubing 52 (see FIG. 1).

In order that the optical system 28 can receive images of the chip 30,the substrate 40 and the compliant member 44, the vacuum chamber 48 isconstructed so that the walls through which an optical axis 54 passesare transparent. It will be noted that the optical axis 54 is also thebonding axis of the machine 20. The uppermost wall is a clear glass orquartz disc 56. Directly below the disc 56 is a clear glass or quartzengagement portion or bonding tip, designated generally by the numeral58. The tip 58 is provided with an aperture or vacuum port 60 throughwhich the force of vacuum within the chamber 48 can be transmitted tothe chip 30.

The chip 30 is shown in "engagement" with the tip 58 under the influenceof the forces of the vacuum source 49. Although the chip 30 is beingheld compressively against the tip 58, there is no actual contacttherewith. The thickness of the compliant member 44 is greater than thethickness of a body portion 61 of the chip 30 and thus, no actualcontact between the chip and the tip occurs in this embodiment during"engagement."

The tip 58 is advantageously provided with a projection 62. Theprojection provides a way of localizing bonding forces to a small regionof one of the substrates 40. This localization is often desirable when anumber of the chips 30 are bonded on one of the substrates 40. Theprojection 62 will fit into a small space on the substrate 40 duringbonding and the likelihood is reduced of disturbing another one of thechips which has previously been bonded nearby on the substrate.

Conventional cartridge heaters 63 are also provided in the head 46 inorder to provide for heating of the chip 30 prior to and during bonding.

It can be seen in FIG. 1 then, that the chip 30 is in a position whereinit can be properly bonded to the metallic elements 38. Bonding isaccomplished by lowering the movable head assembly 22 along conventionalslide assemblies 64. After the assembly 22 is lowered, a conventionalcompliant bond is produced between the leads 36 and the conductiveelements 38. A detailed description of the characteristics andtechniques for producing compliant bonds with polyimide can be had byreferring to an application for U.S. Pat. Ser. No. 864,856 filed in thenames of J. A. Burns and A. Coucoulas on Oct. 8, 1969, and assigned tothe assignee of record of this application.

A substantial amount of heat is required to produce an effectivethermocompression bond and it is found desirable to supplement theheating produced by the heater 63 in the head 46 by heating thesubstrate 40. This is best accomplished by putting conventional heaters65 in a substrate support designated generally by the numeral 66.

After the bond is complete, the head assembly 22 is raised again to theposition shown in FIG. 1. The positioner assembly is moved to the rightalong conventional slide members 68 until a chip tray 70 is positionedon the optical axis 54. The compliant member 44 is also indexed so thata subsequent one of the bonding apertures 42 is aligned with the axis54.

It can be seen from FIG. 1 that the compliant member 44 is a continuousstrip which is wound from a supply reel 72 to a takeup reel 74. Thetakeup reel 74 has torque continuously applied to it by a conventionaltorque motor 76. Control of the movement of the takeup reel 74 isprovided through an indexing sprocket 78.

The indexing sprocket 78 is moved in accurately controlled 45°increments. Movement of the member 44 is initiated when acylinder-actuated pin 80 is withdrawn from one of eight holes 82 in aplate 84. The pin 80 is controlled by a spring-biased cylinder 86 andthe cylinder acts only momentarily to pull the pin out of the hole 82with which it is engaged. As soon as the pin 80 is free from the hole82, the plate 84, which is on the same shaft as the sprocket 78, beginsto rotate because of the force exerted on the sprocket by the member 44.After 45° of rotation the pin 80 snaps into the next one of the holes 82and motion of the compliant member 44 stops. Spacing between bondingaperture 42 is such that 45° rotation of the sprocket 78 results inaccurate location of the subsequent one of the apertures 42 on theoptical axis 54.

After a new one of the bonding apertures is aligned with the opticalaxis 54, an image, such as that shown in FIG. 3, appears on the screen32 of the monitor 28. An operator can see the aperture 42 and theprojection 62 of the tip 58 as well as any one of the chips 30 which iswithin the field of the camera 27. The chips 30 are not necessarily inan ordered array on the chip tray 70 and because of this, it is quitelikely that the chip 30 may not be aligned with the aperture 42.

To achieve alignment, an operator moves a handle 88 of the positionerassembly 26 and rotates the chip tray 70 while viewing the screen 32until the image shown on FIG. 4 is achieved. FIG. 4, of course,illustrates the chip 30 being properly aligned with the aperture 42.

After the image of FIG. 4 is achieved, the head assembly is lowered andthe force of vacuum within the chamber 48 brings the chip 30 intoengagement with the head 46 by being drawn against the compliant member44. After this engagement, the head assembly 22 is raised to theposition shown in FIG. 1.

The positioner assembly 26 is then moved to the left so that one of thesubstrates 40 is roughly aligned with the optical axis 54. At this time,the operator sees an image similar to that shown in FIG. 5 on the screen32.

The operator then moves the positioner handle 88 to manipulate thesubstrate 40 while viewing the screen 32 to achieve alignment of theconductive elements 38 with the leads 36. After an image like that shownin FIG. 6 is achieved, bonding of the leads 36 to the elements 38 cantake place and a full cycle of operation is thus completed.

It is important to note that the vertical movement of the head assembly22 can be quite small. This is because there is no need to place complexoptical system components between the tip 58 and the workpieces. It isdesirable to take advantage of the fact that the movement can be smallso that great precision can be developed in the machine 20.

Keeping the movement of the assembly 22 small also assures that theimage of the aperture 42 and the image of the chip 30 supported on thetray 70 as well as the image of the conductive elements 38 supported onthe substrate holder 66 are simultaneously within the depth of field ofthe optical system 28. It is also important to construct the machine 20so that the chips 30 and the conductive elements 38 are supported atsubstantially the same elevation so that each of the respective imageswill be in focus when they are placed on the optical axis 54 by movementof the positioner assembly 26.

Another embodiment of the inventive apparatus illustrated in FIG. 7includes a non-compliant bonding head, designated generally by thenumeral 146. The bonding head includes a vacuum chamber 148, a vacuumport 150, a transparent disc 156 and a transparent bonding tip 158. Thehead 146 can be used on a bonding machine similar to that shown in FIG.1 with the exception that it is not necessary to use a compliant member.The head 146 is designed to be used in a so-called "hard tip" mode ofoperation. Provision must be made for permitting "compensation" toequalize bonding forces to all of the leads 36. One machine in which thehead 146 may be advantageously employed is described in U.S. Pat. No.3,475,814 issued to J. A. Santangini on Nov. 4, 1969. The head 46 mayalso be incorporated into a "compensating" arrangement by pivotallymounting the head.

The tip 158 includes a projection 162 and an aperture 160. The aperture160 is large enough so that the body portion 61 of one of the chips 30will fit into the aperture with some clearance around all sides of thebody portion. The relative size of the aperture 160 to the body portion61 is shown quite clearly in FIG. 9. The projection 162 servessubstantially the same purpose as the projection 62 (FIG. 2).

Some heat is transmitted through the tip 158 from cartridge heaters 163.Of course, it is still desirable to provide heating from sources otherthan the ram 146.

In using the ram 146, an operator usually first encounters a situationin which the aperture 160 is misaligned with respect to one of the chips30 such as that shown in FIG. 8. This is somewhat analogous to thesituation shown in FIG. 3. The chip 30 is moved into proper alignmentwith the aperture 160 while being viewed along an optical-bonding axis164 through an optical system that is operative because of thetransparency of the disc 156 and the tip 158. FIG. 9 represents an imagethat an operator sees after proper alignment of the chip 30 and theaperture 160 is achieved.

FIG. 10 illustrates the conductive elements 38 of one of the substrates40 as they appear to an operator prior to final aligment of thesubstrate and the chip 30. The substrate 40 is carefully moved until theconductive elements 38 are properly aligned with the leads 36.

FIG. 11 illustrates an image that an operator sees during bonding of theleads 36 to the elements 38. One of the very significant advantages ofthis inventive apparatus is that it permits an operator to visuallydetermine the extent of "squash out" of the leads 36 while bonding isproceeding. Thus, an operator has full visual capabilities for viewing abonding process as it occurs. The operator can respond to excessive orinsufficient "squash-out" and the likelihood of getting good qualitybonds is greatly enhanced with this system.

Another embodiment of the inventive apparatus is illustrated in FIGS. 12through 18. A bonding machine, designated generally by the numeral 180,includes a ram assembly, designated generally by the numeral 182; a chiphandling assembly, designated generally by the numeral 184; a substratepositioner, designated generally by the numeral 186; and an opticalsystem, designated generally by the numeral 188.

Here again an understanding of the structure and operation of themachine 180 can best be understood by discussion of one full cycle ofthe operation. FIG. 12 illustrates the ram assembly 182 in a raisedposition prior to alignment of one of the chips 30 supported on the chiphandling assembly 184. The ram assembly 182 is raised by the action ofan eccentric cam 189 rotating on a shaft 190 causing displacement of aroller 192 connecting to a lever arm, designated generally by thenumeral 194. The lever arm pivots around a fulcrum 196. An engagementportion of the arm 194 presses against an adjustably positionable collar200 when the cam 189 rotates to the position shown in FIG. 12, thusurging the ram assembly 182 upwardly against the force of a compressionspring 202.

While the ram assembly 182 is raised, a tip 203 is held with its lowermost surface approximately 0.015 inch from the surface of a transparentchip tray 204 of the chip handling assembly 184. This spacing can bevaried by adjusting the collar 200 to assure that the chip 30 and thetip 203 are within the depth of field of the optical system 188.

When the tip 203 is held just above the tray 212, the optical system 188can be used to produce an image of both the tip 203 and one of the chips30. The optical system 188 is illustrated in FIG. 12 as being aconventional TV camera with a conventional right angle lens system thatcan be set to view along an optical axis 206. A microscope might also beused with equal success.

The optical axis is aligned with the bonding axis of the machine 180 anda support member 207 is provided with an aperture 208 through which theoptical system 188 can receive the image of the chip 30 and the tip 203.

The chip handling assembly 184 is manipulated in the X and Y directionby a conventional manipulator 210. Angular manipulation is accomplishedby rotating the tray 204. During manipulation an operator views the tip203 and the chip 30 through a screen 212 of a monitor designatedgenerally by the numeral 214 (FIG. 13), associated with the opticalsystem 188. When the chip 30 is aligned properly with the tip 203, thetip is lowered to the position shown in FIG. 15, vacuum is appliedwithin a bonding head 216 the chip 30 is held against the tip 203. Thebonding head is advantageously of the type shown in U.S. Pat. No.3,452,917 issued to F. J. Schneider on July 1, 1969. An image of one ofthe chips 30 properly aligned with the tip 203 is shown in FIG. 16.

When the ram assembly 182 is in the pickup position of FIG. 15 a stopmember 218 is engaged with a latch 220 which is operated by a cylinder222. The cylinder 222 is shown in its extended position in FIG. 15. Thestop member 218 is adjustable in length so that the force of the spring202 is not transmitted to the tray 204 by the tip 203.

After the chip 30 and tip 203 are engaged, the shaft 190 is rotated andthe ram assembly 182 is raised. The latch 220 is retracted by thecylinder 222 and the tray 204 is swung away from the optical and bondingaxis 206 under the action of a gear drive positioning mechanismdesignated generally by the numeral 223 of the chip handling assembly184. FIG. 18 is an illustration of the extent to which the chip tray 204is displaced from the axis 206.

With the ram assembly 182 in its raised position, a carefully machinedsubstrate support block, designated generally by the numeral 224, isplaced into engagement with the substrate positioner 186 as shown inFIGS. 17 and 18. The substrate positioner 186 includes two accuratelypositionable stop members 226. the members 226 are positioned byadjustment of micrometer adjusting screws 228.

The support block 224 is provided with two positioning members 230placed at right angles to each other and a spring clamp 232. Asubstrate, designated generally by the numeral 234, is held against themembers 230 by the clamp 232. Conductive elements 236 on the substrateare very accurately positioned with respect to the outer surface of thesubstrate so that the conductive elements become very accurately locatedwith respect to the sides of the block 224. The micrometer screws 228are adjusted so that a desired portion of the substrate 234 lies on theaxis 206 after the block 224 is placed against the stop members 226.Thus, the chip 30 which is engaged with the tip 203 can be bonded at adesired location on the substrate without actual visual control ofalignment of the substrate 234.

Bonding occurs when the ram assembly 182 is lowered with the latch 220withdrawn. Rotation of the cam 188 permits the ram assembly 182 to movedownwardly under the action of the spring 202 until the tip 203 pressesthe leads 36 against the substrate 234, at which time bonding betweenthe leads 36 and the conductive elements 236 takes place with the spring202 providing the bonding force.

The ram assembly 182 is again raising by rotation of the cam 188. Thelatch 220 is moved outwardly, the chip tray 204 is swung back into theaxis 206, and a new cycle of operation can begin.

It can be recognized that in a situation where a number of the chips areto be bonded onto one substrate, that a number of the bonding machine180 can be positioned along an assembly line and each of the substratepositioners 186 can be adjusted to accommodate a particular chiplocation on the substrate. Thus, one of the substrates 234 mounted onone of the blocks 224 can be passed from one of the machines 180 tosuccessive ones of the machine where chips can be bonded at variouslocations on the substrates thereby creating a highly efficientmanufacturing operation. It should also be recognized that such amanufacturing scheme requires that the conductive elements 236 are veryaccurately located with respect to the outer surfaces of the substrates234. The system is quite useful where the conductive elements 236 areproduced by accurate photo-projection techniques.

It is to be understood that the above-described embodiments are merelyillustrative of the principles of the invention, and that variousmodifications may be made from the specific details described withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. In a method of compliant bonding whereinmetal-to-metal bonding of a first workpiece to a second workpiece isaccomplished by the steps of clamping said workpieces together aroundthe desired bond region between a support and a deformable compliantmember, said member being capable of deformation around one of saidworkpieces, and applying sufficient thermal and/or mechanical bondingenergy to said bond region to deform said member around said oneworkpiece and bond said workpiece, the improvement which comprises thesteps of:providing that said compliant member is transparent, andviewing the workpieces through said transparent compliant member whilealigning said workpieces to each other whereby said alignment isfacilitated.
 2. A method for compliantly bonding a first workpiece to asecond workpiece, which comprises:aligning the first workpiece to apredetermined portion of a transparent compliant bonding member saidmember being capable of deformation around one of said workpieces whileviewing the workpiece through the member; engaging the aligned firstworkpiece with the member; aligning the engaged first workpiece with apredetermined portion of the second workpiece while viewing saidworkpieces through the member; and compressively engaging, for apredetermined period, a bonding tip against the said portion of saidsecond workpiece with the first workpiece and the compliant membertherebetween to effect compliant bonding between the workpieces whileviewing said workpieces through the member.
 3. A method forthermocompression bonding a beam-lead integrated circuit chip to asubstrate, which comprises:aligning the chip to a predetermined portionof a transparent tip while viewing the chip through the tip; engagingthe aligned chip with the tip; aligning the leads of the engaged chipwith a predtermined portion of the substrate while viewing the chip andsubstrate through the tip; and compressively engaging for apredetermined period the tip against said portion of said substrate withthe leads of the chip therebetween to effect bonding between the leadsand the substrate while viewing said leads through the tip.
 4. A methodof bonding first workpieces to second workpieces, which comprises thesteps of:supporting a plurality of the first workpieces on a transparenttray; moving the tray into intersecting relationship with a bonding axisof a bonding machine; viewing along the bonding axis with a magnifyingoptical system through the transparent tray to simultaneously visualizea bonding tip and any of the first workpieces or portions thereof whichare on or near the bonding axis; manipulating the supporting tray inresponse to the visualization to align one of the first workpieces withthe tip; moving the tip along the bonding axis to engage the tip withthe aligned first workpiece; moving the tip to a retracted position;moving the tray out of intersecting relationship with the bonding axis;placing a second workpiece into a pre-positionable location so that adesired portion of the second workpiece is aligned with the bondingaxis; and moving the tip and the engaged first workpiece intocompressive relationship with the second workpiece to effect bondingbetween the first workpiece and the desired portions of the secondworkpiece.
 5. The method of bonding of claim 4 wherein the firstworkpieces are beam-lead integrated-circuit chips, the second workpiecesare substrates and bonding is effected between the leads of the chipsand conductive elements formed on the surface of the substrates.
 6. In abonding apparatus, a system for aligning a workpiece with a bonding tipwhich comprises:a transparent tray for supporting the workpiece; opticalmagnification means having a predetermined depth of field for viewingthe workpiece and the bonding tip through the transparent tray; meansfor supporting the transparent tray close enough to the bonding tip sothat the tip and the workpiece are simultaneously within the depth offield of the optical magnification means; and means for manipulating thetransparent tray to align the workpieces with the bonding tip.
 7. Anapparatus for bonding beam-lead integrated circuit chips to conductiveelements on substrates which comprises:a bonding tip; a transparent trayfor supporting a plurality of the chips; means for moving the tray intoand out of intersecting relationship with the bonding axis; magnifyingoptical means for viewing simultaneously the bonding tip and the chipsor portions thereof which are on or near the bonding axis when thetransparent tray intersects the bonding axis; means for manipulating thetray in response to an image of the tip and the chips as seen throughthe magnifying optical means to align one of the chips with the tip;means for moving the bonding tip along the bonding axis to engage thetip with the aligned chip and returning the tip to a retracted position;a removable support block having two intersecting reference surfacesthereon and having a clamp assembly thereon for maintaining a desiredportion of the conductive elements of the substrate at a desiredlocation with respect to the reference surfaces of the block; at leasttwo stop members against which the reference surfaces of the block canbe placed, the stop members being adjustable positionable with respectto the bonding axis, in a plane intersecting the axis, such that thedesired portion of substrate can be aligned with the bonding axis whenthe support block is located against the stop members; and means formoving the bonding tip and the engaged chip into compressive engagementwith the conductive elements of one of the substrates held in thedesired location on the block against the stop members to effect bondingbetween the leads of the chip and the conductive elements of thesubstrate.
 8. Apparatus for thermocompression bonding a first workpieceto a second workpiece, which comprises:a bonding head capable oftransmitting light through at least a tip portion thereof; means foraligning said first workpiece to a predetermined portion of the tip;means for engaging said aligned first workpieces to said tip; means foraligning the engaged first workpiece with a predetermined portion of thesecond workpiece; means for compressively engaging for a predeterminedperiod the tip against the said portion of said second workpiece withthe first workpiece therebetween to effect bonding between theworkpieces; and means for viewing the first workpiece and saidpredetermined portion of the second workpiece through the lighttransmitting portion of the tip whereby said alignment of the firstworkpiece to the tip, the alignment of the first workpiece to the secondworkpiece and the compressive engagement between the workpieces isperformable in response to visual information transmitted through saidviewing means.
 9. The apparatus of claim 8, which furthercomprises:means for engaging a transparent compliant member with the tipwhereby the apparatus can be made capable of producing compliant bonds.10. The apparatus of claim 9 wherein the head comprises:a hollow chamberinternal of said head, the chamber being formed and located so thatbonding axis passes two sides thereof; being closed on one of its sidesthrough which the bonding axis passes by the transparent engagementportion being in communication with the aperture in the engagementportion; being closed at the opposite one of the sides through which thebonding axis passes by a transparent member; and having an aperture inone of the sides other than those through which the bonding axis passeswhich aperture is connectable to the vacuum source whereby theconnection to the vacuum source is remote from the bonding axis andvisibility along the axis is not impaired by such connection.
 11. Theapparatus of claim 8 wherein the bonding head includes a transparentengagement portion and the means for engaging the first workpiece withthe head includes an aperture in said engagement portion connectable toa source of vacuum whereby said first workpiece can be held against saidhead by the forces of the vacuum source.
 12. The apparatus of claim 11wherein the aperture in the engagement portion is shaped to accommodatea body portion of a beam-lead integrated-circuit chip while leads of thechip bear against the engagement portion.
 13. The apparatus of claim 8wherein the bonding head includes a transparent engagement portion whichis quartz.
 14. The apparatus of claim 8 wherein the bonding headincludes a transparent engagement portion which is glass.
 15. In anapparatus for compliant bonding wherein metal-to-metal bonding of afirst workpiece to a second workpiece including means for clamping saidworkpieces together around the desired bond region between a support anda deformable compliant member, said member being capable of deformationaround one of said workpieces and means for applying sufficient thermaland/or mechanical bonding energy to said bond region to deform saidmember around said one workpiece and bond said workpiece, theimprovement which comprises:the compliant member being transparent; andthe apparatus having means for viewing the workpieces through thetransparent compliant member whereby alignment of the workpieces witheach other and with the compliant member is facilitated.
 16. Theapparatus of claim 15 wherein the compliant member is formed of a filmof polyimide film.
 17. In a bonding head wherein a first workpiece to bebonded to a second workpiece is held in engagement with the head on abonding axis prior to engagement with the second workpiece, theimprovement which comprises:the bonding head being transparent along thebonding axis whereby the engaged first workpiece is visible through thehead, the second workpiece is visible through the head when the engagedfirst workpiece overlies the second workpiece and alignment between theworkpieces is facilitated because of such visibility.
 18. The bondinghead of claim 17 which comprises:a transparent engagement portionagainst which the first workpiece bears, and an aperture in saidengagement portion connectable to a source of vacuum whereby said firstworkpiece can be held against said head by the forces of the vacuumsource.
 19. The bonding head of claim 18 which comprises:a hollowchamber internal of said head, the chamber being formed and located sothat bonding axis passes two sides thereof; being closed on one of itssides through which the bonding axis passes by the transparentengagement portion being in communication with the aperture in theengagement portion; being closed at the opposite one of the sidesthrough which the bonding axis passes by a transparent member; andhaving an aperture in one of the sides other than those through whichthe bonding axis passes which aperture is connectable to the vacuumsource whereby the connection to the vacuum source is remote from thebonding axis and visibility along the axis is not impaired by suchconnection.
 20. The bonding head of claim 18 wherein the aperture in theengagement portion is shaped to accommodate a body portion of abeam-lead integrated-circuit chip while leads of the chip bear againstthe engagement portion. .Iadd.
 21. A bonding tool for attaching aplurality of preformed electrical connectors on a semiconductor deviceto a plurality of electrical conductors on a substrate or carrier, saidbonding tool comprising: an elongated body, means on the body formounting the bonding tool on a bonding machine, a central observationopening through the body which is larger than the semiconductor deviceto be bonded, said central observation opening in said elongated bodyhaving a transparent and non diffused field of view therethroughencompassing the area defined by the preformed electrical connectors onthe semiconductor device, and a transparent bonding wedge having asubstantially flat working face thereon mounted on the lower end of thebody in the central observation opening for pressing said preformedelectrical connectors into engagement with said electrical conductors toeffect bonding attachment thereto while observing and aligning theconnectors with the conductors through the central observation opening..Iaddend..Iadd.
 22. A bonding tool as set forth in claim 21 wherein saidtransparent bonding wedge is provided with a central aperture thereinand said working face extends outwardly therefrom. .Iaddend..Iadd.
 23. Abonding tool as set forth in claim 22 wherein said working face on saidbonding wedge projects downwardly away from said bonding wedge to permitthe tip of the bonding tool to pick up a device out of an array of aplurality of devices. .Iaddend. .Iadd.
 24. A bonding tool as set forthin claim 21 which further includes vacuum means attached to the upperpart of body. .Iaddend..Iadd.
 25. A bonding tool as set forth in claim24 wherein said vacuum means provides the means for mounting the bondingtool on a bonding machine. .Iaddend..Iadd.
 26. A bonding tool as setforth in claim 25 wherein said central observation opening is closed atthe top with a transparent cap. .Iaddend..Iadd.
 27. A bonding tool asset forth in claim 22 which further includes a heating coil on theoutside of said body near the transparent bonding wedge. .Iaddend..Iadd.
 28. A bonding tool for picking up and attaching a beam leadsemiconductor device to a conductive pattern on a substrate or carrier,said tool comprising, an elongated body, a central observation openingthrough the length of the elongated body, said opening beingsubstantially larger than the beam lead device to be picked up andbonded to the substrate, a transparent bonding wedge on the lower end ofthe elongated body, an aperture in said bonding wedge smaller than thedevice to be picked up and bonded to the substrate, a working face onsaid bonding wedge extending outwardly and downwardly from said aperturefor engaging only the leads of the beam lead device, and means forconnecting a negative pressure source to said bonding tool whereby abeam lead device is observed and aligned with the bonding wedge duringpickup and the leads of the beam lead device are observed and alignedwith the conductive pattern on the substrate during attachment..Iaddend.